Echinoidea and Ophuiroidea

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Discovery reports.

London ;Cambridge University Press.
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244 DISCOVERY REPORTS

edge is gently convex. The pores have a well-developed tentacle scale (Fig. 3 a). Dorsal
arm plates in the basal part of arms fairly regularly divided into two parts (Fig. 3 b).
Arm spines two on the joints within the disk; beyond the disk there are three spines.
In the proximal part of the arms the lowermost and the uppermost spine enlarged,
somewhat flattened and sometimes a little curved. In the distal part the two uppermost
spines transformed into hooks (Fig. 3 c). The scales of the disk as usual with a glassy,

American

concentrically striated margin. Rather large mainly three-radiate spicules in the
stomach wall (Fig. 3 d). About the colour in life there is no information; the preserved

specimens are white.

It is evident that this species is nearly related to the South African O. dentatus,
Lyman, and it might, indeed, seem questionable whether the small differences to be
observed (cf. fig. 3 with the figures of O. dentatns given in my paper on the South
African Echinoderms, pp. 310-11, figs. 32-4) are really of sufficient value for specific
distinction. Of this there cannot, however, be the slightest doubt, for I find that the

partly — hermaphrodite y whereas O. dentatus y
as well as the closely related O, purpnreus, are not viviparous and have separate sexes.
Thus it is certain that the South American form is a quite distinct species, the more
interesting as this is the first viviparous species of the genus Ophioscolex to be known.

The statement that this species is " partly" hermaphrodite means that some speci-
mens are not hermaphrodite, but purely males or females. Thus the species is a
facidtative hermaphrodite. This is of interest in connection with the fact that the two
known viviparous species of Ophiomyxa have separate sexes. It would seem to be a
beginning of hermaphroditism that we are witnessing in this primitive Ophiurid, herm-
aphroditism in Ophiurids being apparently a specialization acquired in connection

with viviparity.

As regards the arrangement of the gonads in the hermaphrodite specimens it seems
to be the more usual condition that the male gonads are situated at the adradial side, the
female gonads along the interradial side of the bursae, but there is no regularity either in
the arrangement or the number of the gonads. I have found only one or two young ones

at a time in the bursae.

No species of Ophioscolex was known till now from the Antarctic or sub-Antarctic
region, the "Ophioscolex Coppingeri" of Bell being nothing but Ophiomyxa vivipara
(cf. above, p. 242). It is thus a rather surprising fact that no less than two species of the
genus, Ophioscolex natrix and the following species, O. marionis, have been discovered
by the ships of the Discovery Committee in the sub-Antarctic region.

Ophioscolex marionis, n.sp.

St. 1563. 7. iv. 35. 46 48' S, 37 49' E, off Marion Island, 113-99 m - I specimen.

Diameter of disk 5-5 mm. Arms all broken close to the disk; they are 1-5 mm. broad,
somewhat flattened. Disk covered by thick skin, through which some scattered short
spines protrude all over the dorsal side, a single one also here and there on the ventral
interradii. Apparently no radial shields. The buccal shields are small, rounded tn-

OPHIOMYXIDAE

245

angular, adoral shields rather broad, not joining within; they separate broadly the buccal
shield from the first lateral plate. Mouth papillae small, feebly developed. Ventral arm
plates distinctly longer than broad, with convex distal edge, joining broadly at least as
far out on the arms as they are preserved. Dorsal arm plates very feebly developed, as
usual, but covering the whole broad dorsal side between the small lateral plates; they
are not divided in two by a transverse line. Arm spines four, short, robust, the lower-
most and uppermost ones slightly longer than the two middle ones. One tentacle scale.
Colour in alcohol brownish.

The species is clearly viviparous; not that I have actually found embryos within it,
but the eggs are large, ca. 0-2-0-3 mm. and yolky, seven to ten eggs in each gonad; and
then it is hermaphrodite, there being one male gonad at the adradial side and one
or two female gonads at the interradial side of the bursa. As not a single case is known

b

Fig. 4. Ophioscolex marionis, n.sp. a, Part of oral side. 6, Part of dorsal
side of arm. The dotted arch -lines represent the outline of the vertebrae
seen through the exceedingly thin dorsal plates. X15.

of a non-viviparous

iurid being hermaphrodite, we may, I think, safely con-

no spicules are found in the stomach wall, such as occur in

elude that this species must be viviparous, as the character of the female gonads also
indicates.

It may be added
O. nutrix.

That this species is not very closely related to the other Antarctic species of Ophio-
scolex, O. nutrix, is evident enough ; a comparison of the figures will show the differences
in the shape of the buccal shield, ventral and dorsal arm plates, and the mouth papillae,
to which may be added the difference in the number of arm spines, one having three,
the other four spines, which makes an important difference within this genus. It would
appear that the present species is the nearest related to O. quadrispinus, Verrill, from off
Nova Scotia ; this species is, however, scarcely sufficiently well known to allow the dif-
ferences between the two species to be indicated ; but it seems that O. quadrispinus has
no spines on the disk.

246 DISCOVERY REPORTS

It is very regrettable that the arms of the single specimen of O. marionis are all broken,
so that it cannot be seen whether the upper spines are transformed into hooks in the
distal part of the arms, as they are in O. dentatiis-piirpureiis and O. nutrix, a character
which has an important bearing on the question of the validity of the subgenus or genus
Ophiolycus (cf. my paper on the Echinoderms of South Africa, p. 315). If these spines
are not transformed into hooks in O. marionis this species will form a connecting link
between Ophiolycus and the typical Ophioscolex.

Family OPHIACANTHIDAE
Ophiacantha vivipara, Ljungman

(Plate VII, fig. 2)

Ophiacantha vivipara, Ljungman, 1870. On tvanne nya after Ophiurider. Ofvers. Vet. Akad.

Handl., 1870, p. 470.
Ophiocoma (?) vivipara, Wyv. Thomson, 1877. The Atlantic, n, pp. 241-4, fig. 50.
Ophiacantha vivipara, Ludwig, 1899. Ophiuroideen Hamburger Magalh. Sammelreise, p. 13.
O. vivipara, Koehler, 191 2. II e Exped. Antarct. Fran?aise. Echinodermes, p. 138, pi. xi,

figs. 1-2, 10.
O. vivipara, Koehler, 1917. Echinodermes de Kerguelen. Ann. Inst. Oceanogr., vn, 8, p. 71.
O. vivipara, Mortensen, 1920. On Hermaphroditism in viviparous Ophiurids. Acta Zoologica, I,

p. 10.
O. vivipara, Koehler, 1923. Swedish Antarct. Exped. Asteries et Ophiures, p. 105.
O. vivipara, G. A. Smith, 1923. Report on the Echinoderms colL during the voyage of the 'Quest'.

Ann. Mag. Nat. Hist., 9 Ser., xn, p. 368.
O. vivipara heptactis, Hertz. 1926. Deutsche Siklpolar- Exped. Ophiuroiden, p. 36.
O. vivipara, Koehler, 1927. Austral. Antarct. Exped. Echinod. Ophiuroidea, p. 12.
I O. vivipara, Grieg, 1929. Some Echinoderms from the South Shetlands. Bergens Mus. Arbok,

!929> 3> P- 7-

For references to the older literature I may refer to Ludwig, op. cit.

St. 27. 15. iii. 26. West Cumberland Bay, South Georgia, no m. Several specimens,
St. 39. 25. iii. 26. East Cumberland Bay, South Georgia, 179-235 m. 4 specimens.
St. 42. 1. iv. 26. Off mouth of Cumberland Bay, South Georgia, 120-204 m ' Several specimens.
St. 123. 15. xii. 26. Off mouth of Cumberland Bay, South Georgia, 230-250 m. 2 specimens.
St. 140. 23. xii, 26. Stromness Harbour to Larsen Point, South Georgia, 122-136 m. ca. 15
young specimens.

St. 144. 5. i. 27. Off mouth of Stromness Harbour, South Georgia, 155-178 m. 4 specimens.

St. 148. 9, i. 27. Off Cape Saunders, South Georgia, 132-148 m. 1 young specimen.

St. 156. 20. i, 27. 53 51' S, 36 21' W, South Georgia, 200-236 m, 2 specimens.

St. 159. 21. i. 27. 53 52' S, 38 08' W, South Georgia, 160 m. 1 specimen.

St. 160. 7. ii. 27. Near Shag Rocks, South Georgia. 177 m. 5 specimens.

St. 170. 23. ii. 27. Off Cape Bowles, Clarence Island, 342 m. 10 specimens.

St. 175. 2. iii. 27. Bransfield Strait, South Shetlands, 200 m. 2 specimens.

St. 190. 24. iii. 27. Bismarck Strait, Palmer Archipelago, 93-130 m. 3 specimens.

St. 474. 12. xi. 30. Off Shag Rocks, South Georgia, 199 m, 12 specimens.

St. 599. 17. i. 31. 67 08' S, 69 06' W, 203 m. 1 specimen.

St. 652. 14, iii. 31. Burdwood Bank. 171-169 m. 1 specimen.

St. 1562. 7. iv. 35. 46 53' S, 37 55' E, off Marion Island, 90-97 m. 4 specimens.

St. 1563. 7. iv. 35. 46 48' S, 37 39' E, off Marion Island, 113-99 m. 6 specimens.

The following text is generated from uncorrected OCR.
[Begin Page: Page 244]

244 DISCOVERY REPORTS

edge is gently convex. The pores have a well-developed tentacle scale (Fig. 3 a). Dorsal
arm plates in the basal part of arms fairly regularly divided into two parts (Fig. 3 b).
Arm spines two on the joints within the disk; beyond the disk there are three spines.
In the proximal part of the arms the lowermost and the uppermost spine enlarged,
somewhat flattened and sometimes a little curved. In the distal part the two uppermost
spines transformed into hooks (Fig. 3 c). The scales of the disk as usual with a glassy,
concentrically striated margin. Rather large mainly three-radiate spicules in the
stomach wall (Fig. 3 d). About the colour in life there is no information; the preserved
specimens are white.

It is evident that this species is nearly related to the South African O. dentatus,
Lyman, and it might, indeed, seem questionable whether the small differences to be
observed (cf. fig. 3 with the figures of O. dentatus given in my paper on the South
African Echinoderms, pp. 31 0-1 1 , figs. 32-4) are really of suflnicient value for specific
distinction. Of this there cannot, however, be the slightest doubt, for I find that the
South American form is viviparous and — partly — hermaphrodite, whereas O. dentatus,
as well as the closely related O. purpiireus, are not viviparous and have separate sexes.
Thus it is certain that the South American form is a quite distinct species, the more
interesting as this is the first viviparous species of the genus Ophioscolex to be known.

The statement that this species is "partly" hermaphrodite means that some speci-
mens are not hermaphrodite, but purely males or females. Thus the species is a
facultative hermaphrodite. This is of interest in connection with the fact that the two

known viviparous species of Ophiomyxa have separate sexes. It would seem to be a
beginning of hermaphroditism that we are witnessing in this primitive Ophiurid, herm-
aphroditism in Ophiurids being apparently a specialization acquired in connection

with viviparity.

As regards the arrangement of the gonads in the hermaphrodite specimens it seems
to be the more usual condition that the male gonads are situated at the adradial side, the
female gonads along the interradial side of the bursae, but there is no regularity either in
the arrangement or the number of the gonads. I have found only one or two young ones
at a time in the bursae.

No species of Ophioscolex was known till now from the Antarctic or sub-Antarctic
region, the "Ophioscolex Coppingeri" of Bell being nothing but Ophiomyxa vivipara
(cf. above, p. 242). It is thus a rather surprising fact that no less than two species of the
genus, Ophioscolex nutrix and the following species, O. marionis, have been discovered
by the ships of the Discovery Committee in the sub-Antarctic region.

Ophioscolex marionis, n.sp.

St. 1563. 7. iv. 35. 46°48' S, 37°49' E, off Marion Island, 113-99 m- i specimen.

Diameter of disk 5-5 mm. Arms all broken close to the disk; they are 1 -5 mm. broad,
somewhat flattened. Disk covered by thick skin, through which some scattered short
spines protrude all over the dorsal side, a single one also here and there on the ventral
interradii. Apparently no radial shields. The buccal shields are small, rounded tn-

[Begin Page: Page 245]

OPHIOMYXIDAE

245

angular, adoral shields rather broad, not joining within ; they separate broadly the buccal
shield from the first lateral plate. Mouth papillae small, feebly developed. Ventral arm
plates distinctly longer than broad, with convex distal edge, joining broadly at least as
far out on the arms as they are preserved. Dorsal arm plates very feebly developed, as
usual, but covering the whole broad dorsal side between the small lateral plates; they
are not divided in two by a transverse line. Arm spines four, short, robust, the lower-
most and uppermost ones slightly longer than the two middle ones. One tentacle scale.
Colour in alcohol brownish.

The species is clearly viviparous; not that I have actually found embryos within it,

but the eggs are large, ca. o-z-o-t, mm. and yolky, seven to ten eggs in each gonad; and

then it is hermaphrodite, there being one male gonad at the adradial side and one

or two female gonads at the interradial side of the bursa. As not a single case is known

Fig. 4. Ophioscolex marionis, n.sp. a, Part of oral side, b, Part of dorsal
side of arm. The dotted arch-lines represent the outline of the vertebrae
seen through the exceedingly thin dorsal plates. X15.

of a non-viviparous Ophiurid being hermaphrodite, we may, I think, safely con-
clude that this species must be viviparous, as the character of the female gonads also
indicates.

It may be added that no spicules are found in the stomach wall, such as occur in
O. niitrix.

That this species is not very closely related to the other Antarctic species of Ophio-
scolex, O. mitrix, is evident enough; a comparison of the figures will show the differences
in the shape of the buccal shield, ventral and dorsal arm plates, and the mouth papillae,
to which may be added the difference in the number of arm spines, one having three,
the other four spines, which makes an important difference within this genus. It would
appear that the present species is the nearest related to O. quadrispinus, Verrill, from off
Nova Scotia ; this species is, however, scarcely sufficiently well known to allow the dif-
ferences between the two species to be indicated ; but it seems that O. quadrispinus has
no spines on the disk.

[Begin Page: Page 246]

246 DISCOVERY REPORTS

It is very regrettable that the arms of the single specimen of O. marionis are all broken,
so that it cannot be seen whether the upper spines are transformed into hooks in the
distal part of the arms, as they are in O. dentatiis-purpureiis and O. nutrix, a character
which has an important bearing on the question of the validity of the subgenus or genus
Ophiolyciis (cf. my paper on the Echinoderms of South Africa, p. 315). If these spines
are not transformed into hooks in O. marionis this species will form a connecting link
between Ophiolycus and the typical Ophioscolex.

Family OPHIACANTHIDAE

Ophiacantha vivipara, Ljungman

(Plate VII, fig. 2)

Ophiacantha vivipara, Ljungman, 1870. On tvdnne nya arter Ophiurider. Ofvers. Vet. Akad.

Handl., 1870, p. 470.

Ophiocoma (?) vivipara, Wyv. Thomson, 1 877. The Atlantic, 1 1 , pp. 241 -4, fig. 50.
Ophiacantha vivipara, Ludwig, 1899. Ophiuroideen Hamburger Magalh. Sammelreise, p. 13.
O. vivipara, Koehler, 191 2. IP Exped. Antarct. Fran A aise. Echinodermes, p. 138, pi. xi,

figs. 1-2, 10.

O. vivipara, Koehler, 1 91 7. Echinodermes de Kerguelen. Ann. Inst. Oceanogr., vn, 8, p. 71 .

O. vivipara, Mortensen, 1920. On Hermaphroditism in viviparous Ophiurids. Acta Zoologica, i,

p. 10.

O. vivipara, Koehler, 1923. Swedish Antarct. Exped. Asteries et Ophiures, p. 105.

O. vivipara, G. A. Smith, 1 923. Report on the Echinoderms coll. during the voyage of the ' Quest'.

Ann. Mag. Nat. Hist., 9 Sen, xn, p. 368.

O. vivipara heptactis. Hertz. 1926. Deutsche Siidpolar-Exped. Ophiuroiden, p. 36.

O. vivipara, Koehler, 1927. Austral. Antarct. E.xped. Echinod. Ophiuroidea, p. 12.

O. vivipara, Grieg, 1929. Some Echinoderms from the South Shetlands. Bergens Mus. Arbok,

1929,3, p. 7.

For references to the older literature I may refer to Ludwig, op. cit.

St. 27. 15. iii. 26. West Cumberland Bay, South Georgia, no m. Several specimens.

St. 39. 25. iii. 26. East Cumberland Bay, South Georgia, 179-235 m. 4 specimens.
St. 42. I. iv. 26. Off mouth of Cumberland Bay, South Georgia, 120-204 m. Several specimens.
St. 123. 15. xii. 26. Off mouth of Cumberland Bay, South Georgia, 230-250 m. 2 specimens.
St. 140. 23. xii. 26. Stromness Harbour to Larsen Point, South Georgia, 122-136 m. ca. 15
young specimens.

St. 1 44. 5. i. 27. Off mouth of Stromness Harbour, South Georgia, 1 55-1 78 m. 4 specimens.

St. 148. 9. i. 27. Off Cape Saunders, South Georgia, 132-148 m. i young specimen.

St. 156.20. i. 27. 53° 51' S, 36° 21' W, South Georgia, 200-236 m. 2 specimens.

St. 1 59. 21 . i. 27. 53° 52' S, 38° 08' W, South Georgia, 1 60 m. i specimen.

St. 1 60. 7. ii. 27. Near Shag Rocks, South Georgia. 1 77 m. 5 specimens.

St. 1 70. 23. ii. 27. Off Cape Bowles, Clarence Island, 342 m. 1 specimens.

St. 175. 2. iii. 27. Bransfield Strait, South Shetlands, 200 m. 2 specimens.

St. 190. 24. iii. 27. Bismarck Strait, Palmer Archipelago, 93-130 m. 3 specimens.

St. 474. 12. xi. 30. Off Shag Rocks, South Georgia, 199 m. 12 specimens.

St. 599. 1 7. i. 31 . 67° 08' S, 69° 06' W, 203 m. I specimen.

St. 652. 1 4. iii. 31 . Burdwood Bank. 1 71 -1 69 m. i specimen.

St. 1562. 7. iv. 35. 46° 53' S, 37° 55' E, off Marion Island, 90-97 m. 4 specimens.

St. 1563. 7. iv. 35. 46°48'S,37°39' E, off Marion Island, 113-99 m. 6 specimens.